农村生活污水陶瓷膜-生物反应器处理工艺强化脱氮除磷研究

Enhancement of nitrogen and phosphorus removal in ceramic membrane bioreactorfor rural sewage treatment

传统膜生物反应器是农村生活污水处理的重要工艺之一,但其存在氮磷去除效果差等问题,本文旨在探究陶瓷膜生物反应器对农村生活污水的处理效果,并提高其脱氮除磷效果。陶瓷膜-生物反应器(C-MBR)是将好氧生物反应与无机陶瓷平板膜过滤技术相结合的工艺,具有占地面积小、维护简单、排泥量少等优点。本文利用陶瓷膜代替传统膜-生物反应器中的有机膜,对C-MBR进行强化脱氮除磷工艺研究,通过优化回流比、DO、HRT等进行强化脱氮,采用粉煤灰多孔填料吸附进行强化除磷。结果表明:在进水COD和TN、NH_3-N、TP浓度分别为360.00～661.00、33.90～57.60、16.80～32.30 mg·L^(-1)和4.78～5.70 mg·L^(-1),MLSS为3000 mg·L^(-1),膜孔径为50 nm条件下,C-MBR出水对应指标平均浓度分别为34.90、22.59、1.13 mg·L^(-1)和4.57 mg·L^(-1),平均去除率分别为93.68%、47.86%、95.00%和12.32%。优化回流比至200%、DO浓度为2.00 mg·L^(-1)、好氧池HRT为4 h时,TN平均去除率显著提高,最佳可达69.39%,出水平均浓度为12.52 mg·L^(-1),且此时出水稳定、能耗低;粉煤灰多孔填料在水力负荷0.33 m^3·m^(-3)·d^(-1)条件下,对TP去除率可达90.90%,出水平均浓度为0.42 mg·L^(-1),满足一级A标准。使用1000 mg·L^(-1)的次氯酸钠水溶液,以每片膜500mL·30 min^(-1)速度对膜进行在线清洗时,跨膜压差恢复速率最快,膜污染去除效果恢复最佳。优化回流比、DO、好氧池HRT能有效强化C-MBR脱氮效果,填料吸附磷能有效强化除磷效果。本研究为农村生活污水就地处理、提高C-MBR脱氮除磷效果提供了有益参考。

The traditional Membrane Bio-reactor(MBR)is one of the most important treatment methods for rural sewage, but its nitrogen and phosphorus removal efficiency is rather low. Ceramic Membrane Bio-reactor(C-MBR)combines aerobic biological reaction with inorganic flat ceramic membrane filtration, and it requires less maintenance and has less sludge discharge. In this study, the ceramic membrane was used instead of traditional organic membrane. A series of experiments were conducted to study the enhancement of nitrogen removal in C-MBR by optimizing the reflux ratio,dissolved oxygen(DO), hydraulic retention time(HRT), porous filler adsorption was also used to enhance phosphorus removal in C-MBR. When operated under certain condition, the concentrations of chemical oxygen demand(COD), total nitrogen(TN), ammonium nitrogen(NH3-N)and total phosphorus(TP)of inflow were 360.00~661.00, 33.90~57.60, 16.80~32.30 and 4.78~5.77 mg·L^-1, respectively;the corresponding average concentrations of outflow were 34.90, 22.59, 1.13 and 4.57 mg·L^-1, respectively,and the average removal rates were 93.68%, 47.86%, 95.0% and 12.32%, respectively. When the reflux ratio was optimized to 200%, the DO was 2.00 mg·L^-1 and the HRT in the aerobic tank was 4 h, the nitrogen removal of C-MBR was strengthened, and the best TN average removal rate could reach 69.39%, and the corresponding average concentration of outflow was 12.52 mg·L^-1. The packing absorption coulds trengthen phosphorus removal. When operated under optimal hydraulic load in packing absorption tank, which was 0.33 m3·m^-3·d^-1, the removal rate of TP could reach 90.90%, and the average TP concentration in outflow was 0.42 mg·L^-1. In addition, 1000 mg·L^-1 sodium hypochlorite solution had the best cleansing effect when the film was cleaned online at a speed of 500 m·30 min-1 each film, since the membrane had the quickest recovery from pollution under this condition. Our results provide reference for rural domestic sewage treatment as well as MBR nitrogen and phosphorus removal enhancement.